Optimization Of Coupling From A Sub-wavelength Metal Nanoaperture To A Gaussian Mode
Abstract
We model the surface resonance effects in a 1D-array of corrugations
on a metal-dielectric film with a sub-wavelength nanoaperture, following the
earlier work by Moreno et-al [Moreno:2003]. We are interested
in computing the coupling of the highly-directional light field emerging
from the metal nanoaperture to the lowest-order Gaussian mode. We follow
the approach by Vasilyev [Vasilyev:2005], to compute the
coupling to a fundamental Gaussian mode.
We have developed an optimization routine to compute the field emission patterns
from a metal nanoaperture, resonant wavelength and transmission coupling
to fundamental Gaussian mode for various geometrical parameters of the metal
nanoastructure. We optimize for maximum T (power transmittance to the lowest
order mode) and T/L (ratio of transmittance to loss to higher order modes)
assuming the zero absorption so that all reflected light can be potentially
recycled in metal nanocavity.
This optimization work on the geometrical parameters of the cavity can be
useful in fabricating a high Q cavity with desired resonant wavelength for
the future construction of a high-efficiency single-photon emitter.